The entire company is somewhere between 300-500 people.

It literally fits into a few floors of a tower in Bellevue.

Meanwhile... Microsoft essentially bought the land area of a mid sized US city, and turned it into a sprawling corporate complex.

... and that is just their main campus.

Microsoft literally runs a private shuttlebus system in the Seattle-Bellevue-Issaquah area, to get people into and out of their campuses.

They then also have local private taxi services to get people from one building in a larger campus, to another.

There's your scale difference.

Microsoft is essentially a semi-sovereign entity, occupies substantial territoty, got their own police too.

... Valve has something like 5-10 concurrent floors in a single building that is basically on top of a shopping mall.